/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#ifndef SQRT_HPP#define SQRT_HPP#include "ifthenelse.hpp"// template to yield template argument as resulttemplate<int N>class Value {  public:    enum { result = N };};// template to compute sqrt(N) via iterationtemplate <int N, int I=1>class Sqrt {  public:    // instantiate next step or result type as branch    typedef typename IfThenElse<(I*I<N),                                Sqrt<N,I+1>,                                Value<I>                               >::ResultT            SubT;    // use the result of branch type    enum { result = SubT::result };};#endif // SQRT_HPP